TAPS is a rare condition that occurs when there are unequal blood counts between the twins in the womb. Unequal blood counts cause the twins to suffer from an ...SkipNavigationImportantUpdates:RecallonPhilipsRespironicsmedicaldevices|COVID-19vaccinationsPhilipsRespironicsissuedarecallforsomeCPAPandBiLevelPAPdevicesandmechanicalventilators.Learnmore. COVID-19:Wearevaccinatingpatientsages12+.Learnmore:Vaccines&3rdDoses|Testing|PatientCare|VisitorGuidelines|Coronavirus|Self-Checker|EmailAlertsHealthHomeConditionsandDiseasesTwinAnemiaPolycythemiaSequence(TAPS)FacebookTwitterLinkedinPinterestPrintRarePregnancyComplicationsWhatistwinanemiapolycythemiasequence?Twinanemiapolycythemiasequence(TAPS)isaformoftwin-to-twintransfusionsyndrome(TTTS)thatcancomplicatemonochorionictwinpregnancies.Inamonochorionicpregnancy,identicaltwinsshareoneplacenta(afterbirth)andanetworkofbloodvesselsthatsupplyoxygenandnutrientsessentialfordevelopmentinthewomb.ThesepregnanciesaresusceptibletocomplicationslikeTTTSandtwinanemiapolycythemiasequence(TAPS). TAPSisarareconditionthatoccurswhenthereareunequalbloodcountsbetweenthetwinsinthewomb.Unequalbloodcountscausethetwinstosufferfromanimbalanceinredbloodcellsandhemoglobin.Thismeansonetwinisnotreceivingtheappropriateamountofoxygenandnutrientsitneedstodevelopproperly.TAPScanoccurrandomlyorafteranincompletelasersurgerytotreatTTTS.IncontrasttoclassicalTTTS,TAPSiscausedbythejoiningofafewsmallcaliberartery-to-veinvesselconnections(AVanastomoses).Arteriesarethebloodvesselsthatcarryoxygen-richbloodfromthehearttotherestofthebody.Veinsarethevesselsthroughwhichbloodreturnstotheheart.TheseAVanastomosesaretypicallyneartheedgeoftheplacentaandarelessthan1mmindiameter.Thetwinthatlosesbloodiscalledthedonortwin,whiletheonethatreceivesthebloodiscalledtherecipienttwin.WhenTAPSoccurs,therecipienttwinisatriskforsuccessivelyincreasingbloodcount,calledpolycythemia,andthedonortwinforprogressivebloodloss,oranemia.TAPSalsodiffersfromclassicalTTTSinthatamnioticfluidlevelsremainn